<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<script src="./js/jquery-3.4.1.min.js" ></script>

<script src="./js/bootstrap.js" ></script>

<link rel="stylesheet" href="./css/bootstrap.css">
<body>
<button class="btn btn-primary">AA</button>
</body>
</html>